Air processing unit for heating, cooling and ventilating



Nov. 21, 1961 H. c. BlERWlRTH ET AL 3,009,408

AIR PROCESSING UNIT FOR HEATING, COOLING AND VENTILATING Filed June 16, 1958 IN VE N TORS d v m, 5 6M 9% 9 ATTORNEYS.

Nov. 21, 1961 Filed June 16, 1958 H. c. BlERWlRTH ET AL 3,009,408

AIR PROCESSING UNIT FOR HEATING, COOLING AND VENTILATING 5 Sheets-Sheet 2 (IIII [I I A A r I ATTORNEYS.

lNVENTORS Nov. 21, 1961 H. c. BIERWIRTH ET AL 3,009,408

AIR PROCESSING UNIT FOR HEATING, COOLING AND VENTILATING Filed June 16, 1958 5 Sheets-Sheet 4 lNVENTO/PS' m0 m2 I,

By 6W 7 5%,M

ATTORNQS.

Nov- 21, 1961 H. c. BIERWIRTH ET AL 3,009,408

AIR PROCESSING UNIT FOR HEATING, COOLING AND VENTILATING 5 Sheets-Sheet 5 Filed June 16, 1958 /N I/E N TORS ATTORNEYS.

ijnited States 3,009,408 Patented Nov. 21, 1961 This invention relates generally to an air distribution system for heating, cooling and ventilating. More particularly, this invention relates to a novel air processing apparatus for supplying conditioned air to an enclosed space.

The conditioning of the atmosphere within school rooms, and similar enclosures which present complex and highly variable requirements for heating, cooling and ventilating, represents a difiicult problem for which presently known air systems fail to provide an adequate solution. The particular difliculties encountered in schoolhouse heating, cooling and ventilating will be discussed in detail so as to present a full background for the typical requirements which are efiiciently fulfilled for the first time by the present invention. It will be understood, however, that the present invention is not limited in any way solely to schoolhouse structures, but is fully adapted for use in the air heating, cooling and ventilating of any enclosed zone which presents a variety of complex and changing conditions affecting the demands for conditioned air within that zone.

Architects, contractors and air treatment engineers recognize that classrooms frequently require cooling even when the outdoor weather is extremely cold. The cooling of such rooms frequently presents a far more challenging problem than does their heating. Body heat from the students and other persons present in the classroom, lighting fixtures, and radiant heat from the sun as it strikes the walls, windows and roof, frequently produce heat gains within the room which exceed the normal transmission or heat losses from the room to the cold outdoor weather. The number of occupants in classrooms, their physical size, their bodily activities, and their lighting requirements vary greatly from room to room Within a schoolhouse within each room during the course of a day. lower class grades transmit relatively lower total quantities of heat to the room atmosphere than do the older and larger children of the upper class grades. There are also variations from class to class in the amount of lighting required, dependent upon the reading activities of the various grade levels. Such factors as recess and lengths of class periods also result in a variety of different and changing conditions of heat load within various classrooms. Substantial heat is often needed in order to effect initial warming of a classroom during the early morning hours prior to the arrival of the students at the beginning of a school day. After the arrival of the students, the body heat load Within the room is often supplemented by direct sunlight striking against the building as the daylight hours progress. In some instances, one or several of a large number of total classrooms may be subjected to use during the evening hours for adult community activities and the like, requiring the maintenance of proper temperature conditions within only one or a few of a large number of classrooms within a given schoolhouse. It will be apparent, therefore, that conditions within any given classroom may change in a matter of minutes from no heat being required, to heat being required, to cooling being required, and such varying conditions within one room may be entirely different from the varying conditions and requirements of an For example, small children of the immediately adjacent room. The maintenance of comfortable temperatures within every room is a matter of great importance, and it is necessary to eifect the controlled distribution of conditioned air regardless of the outside weather conditions.

Outdoor air provides an economical source of relatively cool air for effecting room cooling during all Weather conditions in which the outside air temperature is lower than a comfortable air temperature desired inside the room. The proper heating, cooling and ventilating system for a schoolhouse classroom is one which can very quickly bring in enough outdoor air, when needed, to offset the internal heat gains within the room and keep the room temperatures from overrunning a thermostat or other control setting. Such a proper distribution system, therefore, must be one that is capable of handling either heated air or cool air in a manner that will provide an absolutely even and uniform distribution of air velocity throughout the room.

A component of critical importance to the over-all system for air heating, cooling and ventilating, in accordance with the air curtain principle of our said co-pending application, Serial No. 729,872, filed April 21, 1958, now abandoned, is the air processing unit. This unit comprises a unitary cabinet structure containing the blower, air filter, dampers and controls for regulating the temperature of the air to be introduced into the room through the air distribution ducts. A system of motorized internal dampers directs either recirculated room air, heated room air, or cool outside air, or a balanced mixture of these, through filter means to the blower, and from the blower to the distribution duct system.

It is the primary object of this invention, therefore, to provide a unitary and self-contained air processing unit for continuously recirculating room air and supplementing it as required with heat and with fresh out: side air in a coordinated cycle of automatic operations, so as to maintain a balanced supply of air at the correct room temperature.

It is another object of this invention to provide within a unitary cabinet structure a novel arrangement of blower, air filter, and coordinately controlled dampers for effecting a balanced supply of air at the correct room temperature.

It is a further object of this invention to provide, in an air processing unit, a special arrangement of superposed upper and lower aligned series of air dampers mounted upon common axes of rotation for simultaneously coordinated but directionally opposed rotational movements.

Further objects and advantages of this invention will become apparent as the following description proceeds, and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

A preferred embodiment of the invention is shown in the accompanying drawing, in which:

FIGURE 1 is a perspective view of a typical two-classroom installation of air processing units of the present invention and having a common heater unit.

FIGURE 2 is a vertical cross sectional view of an air processing unit constructed in accordance with the principles and features of the present invention.

FIGURE 3 is a horizontal cross sectional view taken substantially as indicated along the line '3-3 on FIG- URE 2.

FIGURE 3A is a horizontal cross sectional View taken substantially as indicated along the line 3A-3A on FIGURE 2.

FIGURE 4 is a perspective view of the air processing unit taken from the back side and air inlet end with back closure panels removed to show details of internal construction.

FIGURE 5 is another perspective view of the air processing unit, similar to FIGURE 4, and taken from the front side and air discharge end with front closure panels removed to show details of internal construction.

FIGURES 6 through 10 are fragmentary perspective views of the air inlet end of the air processing unit, with parts removed to show the coordinated operative positions of the plural series of air flow regulating dampers for various operating cycles.

FIGURES ll through 14 are diagrammatic views further illustrating the regulatory control operation of the air processing unit for various operating cycles.

FIGURE 15 is a perspective view of a modified type of air processing unit installed within a room for use with a remotely-located forced air heater unit.

FIGURE 16 is a simplified vertical cross-sectional view of the air processing unit of FIGURE 15.

FIGURE 17 is a fragmentary perspective view of the air inlet end of the air processing unit of FIGURE 16, showing the air flow regulating dampers.

Referring now more particularly to FIGURE 1 of the drawing, there is illustrated a heater unit 10, comprising a conventional furnace and heat exchanger assembly within a closed housing. The furnace may employ any suitable heat source, and for purposes of illustration herein may be considered as either a gas or oil fired combustion device. A discharge flue 12 is provided for waste combustion products. A return air plenum chamber 14 communicates with the upper end of the heater 10 and with a pair of return air ducts 16 and 17. The ducts 16 and 17 extend through corresponding inside walls 18 and 19 of adjacent classrooms A and B. A common wall 20 separates the two classrooms, and the entire heater unit 10 is shown for purposes of illustration as being mounted within a suitable service closet contained wholly within the classroom A. It will be understood that details of heater unit location are the primary concern of the building architect, and the heater unit 10 may be located in any remote position, as within a basement or even a separate adjoining structure when required by local codes. A by-pass air duct 2-2 and a warm air duct 24 extend from the heater unit 18, through the room Wall 18, to an'air processing unit 39 located within the classroom A. Corresponding by-pass and Warm air ducts 23 and 25 communicate through the wall 20 with another air processing unit 32 located within the classroom B. The air processing units 36 and 32 are identical in structure and function, and ditfer only in the symmetry of their interior parts arrangement so that the unit is adapted for right-hand air entry from the heater unit and left-hand air discharge to the distribution duct system. The unit 32 is a left-hand entry, right-hand discharge arrangement. The air processing units 30, 32 are mounted within the respective classrooms A and B upon the floor and against an outside wall 34 entirely below windows 36 thereof. The air distribution duct system may be of the type disclosed in our said coending application, Serial No. 729,872, filed April 21, 1958, now abandoned and is designated generally at 38.

Room air may circulate through the return air ducts 16 and 17 to the heater unit 10, into the return air plenum chamber 14, past the heat exchanger means fired by the furnace within the heater unit 10, and outwardly through the Warm air ducts 24 and 25 into the corresponding air processing units 30 and 32. Alternatively, the same return air flow from each classroom may be by-passed within the heater unit 10 so as to pass directly outwardly through the by-pass air ducts 22 and 23, and without heating, into the air processing units 30 and 32. Room air, therefore, may be circulated from either or both of the classrooms A and B through the heater unit 10 and into the air processing units 30 or 32 either heated or unheated.

Referring now more particularly to FIGURES 2 to 5 of the drawing, the structure of the air processing units will be described in detail. For purposes of illustration, the right-hand discharge type of unit 32 of FIGURE 1 will be described. The various components of the air processing unit 32 are entirely self-contained within a unitary cabinet structure 40, comprising a reinforced frame :2, top and bottom panels 44, 46, and a discharge end panel 48. A centrifugal blower unit 50 is mounted within the right-hand end of the cabinet 40. The blower unit 5t; includes a scroll chamber 54 having a fan inlet 56, and a squirrel cage type of fan blade assembly 58. All moving parts of the blower assembly are supported upon the scroll chamber 54 by means of a Sulky mounting assembly 52, of the type including a rigid steel frame fioatingly mounted upon rubber cushion connectors. A fan drive shaft 60 is coupled by means of a belt 62 to the drive pulley 64 of a 4 HP. long-hour motor 66. Adjusting means 68 permits selection of the elfective motor pulley size for varying the fan speed and hence the air volume for classrooms of various sizes. From 800 to 1200 c.f.m. of air is moved by the blower unit 50. The blower discharge outlet 70 communicates through an acoustically lined divider wall 72 with an outlet chamber 74. A discharge opening 76 is formed in the end wall 48 of the cabinet 40, through which the discharged air is directed into the distribution duct system.

A hammock filter 80, comprising a sandwich-type frame of wire mesh enclosing Fiberglas filter material, arcuately overlies the blower unit 50. The Fiberglas filter material extends laterally beyond the side edges of its frame so as to effect edge-sealing engagement with suitable back and front side panels 82 of the cabinet structure 40. During operation, the blower unit 50 draws air at a substantial velocity from the left-hand end of the air processing unit through the hammock filter for discharge outwardly through the opening 76 at the far right-hand end of the air processing unit. The structural details and operational advantages of the hammock filter are fully set forth in our co-pending application, Serial No. 729,935, filed April 21, 1958. Alternatively, a filter structure as described in R. W. Eichorn Patent No. 2,771,963, having a common assignee with the present invention, may be used.

In order to deliver a supply of air which is particularly temperature conditioned for the demands which are to be met within the classroom, a novel arrangement of dampers and controls are provided within the air processing unit 32 upstream of the hammock filter 80 and blower unit 50. A generally horizontal divider panel provides an air flow separating deck. An angularly inclined divider panel 92 provides a further and diagonal air flow separating Wall. In this way, the upstream end of the cabinet structure 40 is compartmented into a recirculated air chamber 94 and a fresh air chamber 96. The shape of the fresh air chamber 96 is that of a right-angular wedge. A similar wedge-shaped zone remains in the upper portion of the air processing unit at the level of the fresh air chamber 96, and this latter zone communicates directly downwardly with and forms a part of the recirculated air chamber 94. In this way, recirculated air (both bypass through damper 93 and warm through damper 100) is admitted into the same chamber 94 but not into the chamber 96.

The left-hand or air inlet end of the cabinet structure 40 is fully open, and is adapted for selective closure by means of an upper and lower series of vertically parallel dampers. The upper series of dampers is indicated collectively at 98, and serves to control the flow of by-pass room air from the duct 23 of the heater unit 10 into the air processing units recirculated air chamber 94. The lower series of dampers, indicated collectively at 100, similarly serves to control the flow of heated recirculated room air from the warm air duct 25 of the heater unit 10 into the chamber 94.

A lower series of vertically parallel dampers, indicated collectively at 102 are mounted at the inward and lower end of the recirculated air chamber 94 for regulating the passage of recirculated room air, both by-pass air from duct 23 and warm air from duct 25, through the chamber 94 to the filter 80 and blower unit 50.

The fresh air chamber 96, defined by the divider panels 90 and 92, communicates through an opening 104 in the back side panel 82 with a source of fresh outside or cold air. An upper series of vertically parallel dampers, indicated collectively at 106, are provided for regulating the flow of outside air from the chamber 96 to the filter 80 and blower unit 50. v

The separate damper elements of each of the series 98, 100 and 102, 106 are arranged for rotation about vertical axes of rotation, and provide sufficient edge overlapand positive engagement when fully closed so as to eifectively cut-ofl the corresponding duct and fresh air flows into the air processing unit.

As will be seen, recirculated room air, either heated or by-passed, is introduced into chamber 94 and passes therefrom-into the air filtering and blower portion of the unit. Fresh air is received in chamber 96 and is directed therefrom into the same air filtering and blower portion of the unit. These two separate air supplies are then mixed and intermingled and discharged from the outlet 76. For this purpose, the inlet of the blower unit 50 is disposed within an air mixing chamber defined by the walls of the cabinet 40 and the dampers 106 and 102 at the outlet end of the unit. The selective and quantitative mixing of by-pass, heated, and fresh air supplies constitutes a processing operation with respect to the nature of the air finally discharged from the unit.

It is an important feature of the present invention that the superposed upper and lower aligned series of air dampers are mounted upon the same or common axes of rotation for simultaneously coordinated but functionally op posed rotational movements. That is, when the lower series of recirculated air dampers 102 are moved to their full closed position, the upper series of fresh dampers 106 are moved to their full open position, and vice versa. When either set of dampers is partially open, the other set is likewise partially open to a complementary extent. In the same way, when the upper series of by-pass air dampers 98 are moved from full closed to full open positions, the lower series of warm air dampers 100 are simultaneously moved from full open to full closed positions.

A bypass and warm air damper actuator motor 108 is fixedly supported by the cabinet frame at the bottom thereof. A suitable operator arm and drive link connection 110 pivotally couples a reciprocated power shaft of the motor 108 directly to each of the series of Warm air dampers 100 by means of a common actuator bracket 111 for simultaneous rotation of the series of dampers by the motor 108. This operation is best illustrated in FIGURE 2, wherein the dampers are shown full-open in solid line and full-closed in dotted line. In this way, selective directional energization of the motor 108 serves to efiect opening or closing movement, as required, of the entire series 100. The by-pass air dampers 98 are mounted on the same vertical rotation shafts as the warm air dampers 100, and effect simultaneous but functionally opposed movements, as a series, when the dampers 100 are shifted between full-open and full-closed positions.

A fresh and recirculated air damper actuator motor 112 is also fixedly supported by the cabinet frame at the bottom thereof, and is pivotally coupled by means of an operator arm and drive link connection 114, and a common actuator bracket 115, to each of the series of recirculated air dampers 102 for simultaneous controlled movements or" both the recirculated and fresh air dampers 102 and 106 in functionally opposed directions, in the same way as dampers 90 and 100.

It is important to note that the operative location of fresh air admission and mixing with recirculated air and heated air is remote relative to, and entirely independently of, the heater unit 10. In this way, the air processing apparatus eliminates such problems as freeze-up, condensation, and corrosion which often result from the temperature extremes and combustion by-products which characterize a heat exchanger device.

The practical operation of the air processing unit will now be set forth so that the unique advantages and features of the structural arrangement heretofore described will be made more apparent. Referring particularly to FIGURES 6 through 14 of the drawing, a series of operative damper positions for various air control requirements has been illustrated. In FIGURE 6, a night operating cycle for a condition of no occupancy within the classroom is illustrated, with the air processing unit per-forming a fuel-saving cycle for continuously recirculating room air, With heating as required to maintain building temperature. The fresh air dampers 106 are completely closed. Accordingly, the recirculated air dampers 102 are "completely open. The by-pass air dampers 98 are fully closed, and the warm air dampers 100 are correspondingly fully open. The heater unit 10 will be controlled by a room thermostat so as to cycle on and oif during the night hours in accordance with the maintenance of a desired low night temperature within the classroom. A thermostatic control device and electrical circuitry for performing such actuating regulation of the heater unit furnace and energization of the damper control motors 108 and of the air processing unit, is disclosed in our co-pending application, Serial :No. 729,974, filed April 21, 1958. The room air is continuously recirculated by the blower of the air processing unit, which runs at all times regardless of the particular operating cycle being performed, and such recirculated air is periodically heated as it passes through the heat exchanger of the heater unit 10 so as to maintain the desired low temperature within the classroom and without the addition of outside air. This operating cycle is further illustrated by FIGURE 11.

In FIGURE 7, an alternative night operating cycle,

where no heat is desired, has been illustrated. The fresh air dampers 106 are closed, the by-pass dampers 98 are open, the warm air dampers 100 are closed, and the recirculated air dampers 102 are open. Under such a set ting of the dampers, room air will be continuously recirculated without the addition of either heat or outside air.

In FIGURE 8 of the drawing, a day operating cycle for occupancy when heat is required while providing a minimum necessary supply of outside air, has been illustrated. When the operation of the air processing unit is switched from night time to day time regulation, the fresh air dampers 106 are opened to theextent desired in order to supply the necessary amount of continuous fresh outside air required by local building codes. This amount is 7 adjustable between 10% and 50% of the total air introduced into the room by the air processing unit. When heating is being performed during the day time, the air processing unit serves to continuously pull in the required amount of fresh outside air. The fresh air dampers 106 are open partially, to an extent pre-set in order to provide the desired amount of outside air, within the 10% to 50% adjustment range, the by-pass air dampers 98 are fully closed, the warm air dampers 100 are fully open, and the recirculated air dampers are partially open to an extent which is complementary to the opening of the fresh air dampers 106.

When changing from the night time setting of FIGURE 6 to the day time setting of FIGURE 8, it is highly important that a start-up delaybe imposed. The fresh air dampers 106 should remain closed, and the recirculated air dampers 102 remain open, as the heater unit 10 provides heat to raise thetemperature of the room air previously being recirculated to a desired level for comfortable occupancy. After the room'has come up to temperature with 100% heated recirculated air, then the fresh air and recirculated air dampers are moved simultaneously to their partially Open positions for introducing a balanced quantity of outside air in accordance with FIGURE 8.

A predetermined slow operation of approximately 40 seconds is required by the actuator motor 108 to switch the fresh air dampers 106 from their partially open positions, for providing the desired 10% to 50% outside air, to their full open positions. It is contemplated that thermostatic control for actuating the damper operation should be sufiiciently sensitive so as to effect a making and breaking of thermostatic contacts several times during this 40 second period. As a result, the fresh air dampers 106 will modulate or hunt to the position required for maintaining proper room temperature.

In FIGURES 9 and -13 of the drawing, a day operating cycle for occupancy when no heat is required while providing a minimum necessary supply of outside air, has been illustrated. The fresh air dampers 106 are partially open at their minimum predetermined setting, the by-pass air dampers 98 are fully open, the warm air dampers 100 are fully closed, and the recirculated air dampers 102 are partially open in coordination with the partially open fresh air dampers 106. In this way, continuous room air circulation without heating is effected, while also introducing the supplemental supply of fresh outside air.

In FIGURES l and 14 of the drawing, a day operating cycle for occupancy when cooling is required has been illustrated. The fresh air dampers 106 are fully open, the bypass air dampers 98 are fully open, the warm air dampers 100 are fully closed, and the recirculated air dampers 102 are fully closed. In this way, no room air will be recirculated and no heating will be performed, and a continuous supply of cool, fresh outside air will be introduced into the room.

The operation and structure of the individual air processing unit has thus far been described, and provides a disclosure of the present invention for the servicing of a single room by a single air processing unit having its own independent heater unit. Where, however, two or more air processing units are coordinately operated with a single heating unit, as in the arrangement illustrated in FIGURE 1, the damper operations of the respective units may be correlated. The operation of the dual system shown in FIGURE 1 in a novel reversal manner will now be described.

For purposes of illustration, it will be assumed that the desired temperatures within classrooms A and B are in balance. The pre-set temperature of one room may, of course, be different from the corresponding desired temperature in the other room. Since neither room requires heat under such conditions, the furnace of the heater unit will be off. It may be further assumed that a typical day operating cycle is to be performed by the air processing units of both classrooms, and that the fresh air dampers 106 and the recirculated air dampers 102 will be partially open. The by-pass air dampers 98 will be closed and the warm air dampers 100 will be open in both of the air processing units 30 and 32.

If a demand for heat occurs in one of the classrooms, say in classroom B, the heater unit furnace will be started. The relative positions of the dampers in the air processing unit 32 of classroom B will remain the same. In classroom A, however, the by-pass air dampers 98 will be moved from their closed position to an open position, and the warm air dampers 100 will correspondingly move from their open position to their closed position. In this way, heated air will be supplied to classroom B in accordance with its demand for an increased room temperature, while the recirculated room air for classroom A will be by-passed so that no furnace heat will be added to it. The corresponding sets of dampers of the two units 30 and 32 are, in effect, in reversed relation.

If a demand for heat should thereafter occur in classroom A, the by-pass dampers 98 will be moved to their closed positions, and the warm air dampers 100 will be correspondingly opened. In this way, classroom A will be supplied with heated air in the same way as classroom B.

If one of the classrooms should stop calling for heat, say classroom B, the dampers of unit 32 will be actuated so that the bypass dampers 98 are opened and the warm air dampers 100 are closed. Now, if classroom A stops calling for heat, there is no longer a demand for heat in either of the classrooms and the furnace of the heater unit 10 will be turned off. The by-pass dampers 98 of unit 32 in classroom B will be closed, and its warm air dampers 100 opened, thus returning to the initial condition when both rooms were in balance and neither required any heat. In this Way, recirculated room air is drawn over the heat exchanger of the now shut-off heater unit 10 to remove the residual heat therefrom. This coordinated operation of the two air processing units permits one of the rooms to be heated for occupants without in any way effecting an over-heating of the other room. For example, it may be desirable to use one classroom during evening hours when the other classroom is on a night operating cycle. In addition, the burner on-off temperature amplitude will be kept small.

It will be understood that cordinated night operation of the air processing units for the two classrooms A and B will be the same as the operation previously described in connection with a day cycle, except that neither room will be supplied with any outside air. Although the reversal damper coordination between the two air processing units 30 and 32 provides a desirable and advantageous sequence for efiicient and economical utilization of the heater unit 10, the air processing units may also be readily operated with identical damper movements in accordance with the particular temperature damands of each room.

Referring now to FIGURES 15 through 17 of the drawing, we have illustrated an alternative embodiment of the air processing unit of the present invention, as modified for those types of in-the-room installations which are particularly adapted to receive heated air under pressure from a remotely located forced-air heater unit. In FIG- URE 15 we have illustrated a typical forced-air installation within a classroom C having an inside wall 120, an outside wall 122 with windows 1124, and a floor 126. A modified form of air processing unit is mounted at a corner of the room against the outside wall 122 and below the windows 124. The air discharge outlet of the unit 130 communicates with an air distribution duct system designated generally at 132. The air processing unit 130 is fully enclosed by a cabinet structure 134. An outside air inlet duct 136 communicates through the outside wall 122 with the interior of the cabinet 134-, and an air inlet grille 138 permits entry of recirculated room air. A forced warm air inlet duct 140 communicates through the bottom wall of the cabinet 134.

As best seen in FIGURE 16, the cabinet 134 serves to enclose a blower unit 142 and a filter assembly 144, identical with the blower unit 50 and the filter assembly 80, respectively, of the previously described air processing unit 32. An upper series of fresh air dampers 146 and a lower series of warm and recirculated air dampers 148 are mounted for coordinated air flow regulating movements by a motor 149, in a manner identical with the dampers 106 and 102 of air processing unit 32. A diagonal partition wall 150 and a horizontal deck 152 serve to provide isolation of a fresh air inlet compartment communicating with the outside air inlet duct 36. The fresh air dampers 146 serve to regulate the flow of fresh outside air to the blower unit 142, again in the same manner as in air processing unit 32. The compartment-defining means 150 and 152 are indicated fragmentarily in FIGURE 16 9 but are omitted from FIGURE 17 to better show the warm air damper structure to be hereinafter described.

A warm air inlet housing 154 defines a plenum cham her 156 having an inlet opening 158 adapted to communicate with the forced warm air inlet duct 14!), and having an outlet opening 160 adapted to communicate with the downstream interior or recirculated air chamber 161 of the cabinet 134 and the blower unit 142 through the warm and recirculated air dampers 148. A damper plate 162 is pivotally mounted on a shaft 164 to provide an adjustabfly movable closure for the Warm air plenum outlet 160. A motor 168 having a reciprocable power shaft is supported by a cabinet 134 at the upper rear wall portions thereof. An adjustable linkage assembly 17s pivotally interconnects the motor power shaft with the pivotable damper plate 162. In this way, selective directional energization of the motor 168 serves to effect opening and closing 'movement of the damper plate 162 over the warm air plenum outlet opening 160.

It will be understood that the practical operation of the unit 130 is similar to that of the unit 132, for achieving the identical operating results of conditioned air supply to a room, except that the double series of warm and recirculated air dampers are replaced by the constantly open recirculated room air grille 138 and the regulatably opened and closed Warm air damper 162. When heat is called for within the classroom C, the warm air damper 162 will be opened. A supply of warm air fed under pressure to the plenum chamber 156 is then permitted to pass into the interior of the air processing unit cabinet 134, through the warm and recirculated air dampers 148 to the blower unit 142, and then into the air distribution duct system 132. The total quantity or" warm air constantly supplied to the air processing unit 130 must necessarily be less than the total quantity of air circulated by the air processing unit through the air distribution duct system 132 so that warm air will not be forced outwardly through the grille 138 directly into the classroom C.

It will be understood that all practical embodiments of applicants invention described herein will comprise essentially the same basic components of cabinet and damper structure. All embodiments require an elongated housing having a cross-wall spaced intermediate the ends of the housing to divide it into an air mixing chamber adjacent the outlet end and a recirculated air chamber adjacent the inlet end. The cross-wall uniquely comprises a pair of separately operable damper means, as indicated by the damper structures 1% and M2 of applicants first embodiment and the damper structures 146 and 148 of applicants second embodiment. Internal wall means extending from the cross-wall serve to form the fresh air chambers of both embodiments within the recirculated air chambers thereof. In the first embodiment another pair of damper means-98 and 109 serves to control the incoming flow of recirculated and heated air respectively, whereas in the second embodiment a single additional damper 162 is provided for control of the heated air only. By selectively opening and closing the pair of damper means of the cross-wall, and the additional damper means controlling the admission of both room air and heated air to the recirculated air chamber, there is provided a mixing of selected air sources within the mixing chamber and blower means for discharge of the desired treated air at the outlet end of the air processing unit.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is intended in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An air processing unit for continuously recirculating 10 room air and conditioning the flow thereof with heated air and with fresh outside air comprising, an elongated housing having a plurality of longitudinal walls and a cross-wall spaced from one end thereof and positioned between said longitudinal walls to divide said housing into an air mixing chamber adjacent said one end and a recirculated air chamber adjacent the other end, said crossvvall comprising first and second immediately-adjacent separately operable damper means forming two separate air passages in the cross-wall, a room air outlet in said one end communicating with said air mixing chamber,

blower means mounted in said air mixing chamber to direct the flow of air through said housing to said room air outlet, a fresh air inlet in a longitudinal wall of said housing adjacent said other end, internal wall means defining a closed conduit with said longitudinal walls extending from said cross-wall at a line between said first and second damper means to said fresh air inlet to form a fresh air chamber within said recirculated air chamber which communicates with said air mixing chamber through said first damper means, a heated air inlet and a room air inlet communicating with said recirculated air chamber, damper means mounted in said heated air inlet, means for selectively opening and closing the damper means in said cross-wall and the damper means in the heated air inlet to provide to said air mixing chamber and blower means a controlled flow of room air and heated air from said recirculated air chamber, and a controlled flow of fresh air from said fresh air chamber for mixing in variable selected proportions by said blower prior to discharge thereby through said room air outlet.

2. An air processing unit for continuously recirculating room air and conditioning the flow thereof with heated air and with fresh outside air comprising, an elongated housing having a plurality of longitudinal walls and a cross-wall spaced from one end thereof and positioned between said longitudinal walls to divide said housing into an air mixing chamber adjacent said one end and a recirculated air chamber adjacent the other end, said crosswall comprising first and second immediately-adjacent separately operable darn-per means forming two air passages in the cross-wall, a room air outlet in said one end communicating with said air mixing chamber, blower means mounted in said air mixing chamber to direct the flow of air through said housing to said room air outlet, a fresh air inlet in a longitudinal wall of said housing adjacent said other end, internal wall means defining a closed conduit with said longitudinal walls extending from said cross-wall at a line between said first and second damper means to said fresh air inlet to form a fresh air chamber within said recirculated air chamber which communicates with said air mixing chamber through said first damper means, a heated air inlet and a room air inlet communicating with said recirculated air chamber, damper means mounted in said heated air inlet, means for simultaneously coordinating the directionally opposedcpening and closing of the damper means in said cross-wall and the damper means in the heated air inlet to provide to said air mixing chamber and blower means a controlled flow of room air and heated air from said recirculated air chamber, and a controlled How of fresh air from said fresh air chamber for mixing in variable selected proportions by said blower prior to discharge thereby through said room air outlet.

3. An air processing unit for continuously recirculating room air and conditioning the flow thereof with heated air and with fresh outside air comprising, an elongated housing having a plurality of longitudinal walls and a cross-wall spaced from one end thereof and positioned between said longitudinal walls to divide said housing into an air mixing chamber adjacent said one end and a recirculated air chamber adjacent the other end, said crosswall comprising first and second immediately-adjacent separately operable damper means forming two separate air passages in the cross-wall, a room air outlet in said 1 1 one end communicating with said air mixing chamber, blower means mounted in said air mixing chamber to direct the flow of air through said housing to said room air outlet, a fresh air inlet in a longitudinal wall of said housing adjacent said other end, internal wall means defining a closed circuit with said longitudinal walls extending from said cross-wall at a line between said first and second damper means to said fresh air inlet to form a fresh air chamber within said recirculated air chamber which communicates with said air mixing chamber through said first damper means, a heated air inlet and a room air inlet communicating with said recirculated air chamber, another pair of immediately-adjacent damper means mounted respectively in said heated air and said room air inlets forming two separate air passages, means for selectively opening and closing said first and second damper means in said cross-wall and said first and second damper means in the room air and heated air inlets to provide to said air mixing chamber and blower means a controlled flow of room air and heated air from said recirculated air chamber, and a controlled flow of fresh air from said fresh air chamber for mixing in variable selected proportions by said blower prior to discharge thereby through said room air outlet.

References Cited in the file of this patent UNITED STATES PATENTS 1,927,869 Downs Sept. 26, 1933 2,327,663 Otis Aug. 24, 1943 2,699,106 Hoyer Jan. 11, 1955 2,775,188 Gannon Dec. 25, 1956 FOREIGN PATENTS 379,430 Great Britain Sept. 1, 1932 

